In the hot rolling process for manufacturing hot rolled products, such as blooms and beam blanks, the workpieces are usually reheated after being rolled in a previous rolling step or as produced by a casting machine to bring the workpieces up to an uniform proper rolling temperature for a subsequent rolling process where the workpieces are further reduced.
The reheating is usually accomplished by a reheating furnace, in which the workpieces are brought to the entry side of the furnace, charged into and passed through the furnace after which the workpieces are discharged at the delivery side of the furnace and transferred away. An example of such furnaces can be found illustrated and described in the publication "The Making, Shaping, Treating of Steel", 10th Edition, 1985, Section 3 entitled "Reheating Furnaces", starting at page 850.
In certain applications, it is important that the workpieces be not pushed into or through the furnace but be carried so as not to damage the surfaces of the workpieces. For this reason some furnaces have been designed with walking beams consisting of a conveyor that carries the workpieces in a step by step fashion, the above publication illustrates and describes such conveyors in a sub-section entitled "Walking Beam Type Furnace" on page 851.
When employing a walking beam type furnace in the above context there must be provided a mechanism for carrying one at a time the workpieces from a position in front of the furnace to a position inside the furnace and placing the workpiece gently on the walking beam conveyor. A similar device, known as an extractor, are provided at the discharge end of the furnace for removing the workpiece and placing it on a table. In the past the workpiece carrying mechanism has been characterized by being expensive to manufacture, unpredictable in operation, not capable of continually accomplishing the required carrying action and costly to maintain.
In addition past chargers and extractors included a hold down or counter balance mechanism for the rams or arms that traversed into and out of the furnace during the workpiece handling operation. This counter balance was accomplished by separate stands for each arm having spring loaded rollers to hold down the arms in their extreme back positions, i.e. when retracted away from the furnace. Incorporated in the roller arrangement for each arm was an arm elevating device designed to hold down the arm and act as a counter balance for the arm.